Intracorneal Ring Segments (ICRS) for Keratoconus

Modern Options for Treating Keratoconus

Intracorneal Ring Segment (ICRS) Implantation

The femtosecond laser — whose underlying physics was developed by the Egyptian Nobel laureate Dr. Ahmed Zewail —

is one of the key advances that have driven progress in corneal surgery in recent years,

and has made intracorneal ring segment (ICRS) implantation easier and far more precise.

Keratoconus is widespread in our region.

The growth of LASIK has helped surface large numbers of cases,

typically during the screening tests performed before LASIK,

where keratoconus is detected — a condition that significantly

affects visual quality and acuity. Several treatment pathways exist for keratoconus,

and this article focuses on intracorneal ring segments (ICRS).

Intracorneal ring segments for keratoconus

Intracorneal ring segments have been used for many years to treat myopia and keratoconus.

The older technique relied on manual instruments used by the surgeon

to create a tunnel inside the cornea into which the ring segments were inserted.

This was later replaced by the femtosecond laser to create the tunnel,

which reduces operating time and creates the tunnel with precise depth and length —

and that precision substantially improves visual quality.

How Do the Rings Improve Visual Quality?

The ring segment is inserted into a tunnel prepared for it.

Because it is made from a rigid polymer, it acts almost as a tensioner

that reshapes the cornea from a steep, conical shape toward a more natural curvature —

which improves the quality of the image formed on the retina.

The cornea may need one or two ring segments,

depending on the corneal topography map.

Are Rings Right for You?

– In very advanced keratoconus, where the corneal steepening (Kmax) exceeds 75 D —

some clinical schools prefer not to operate above 55 D —

or where there are corneal opacities or scars, ICRS is generally not appropriate.

ICRS is also unsuitable when corneal thickness is less than 300 microns.

Summary

Intracorneal ring segments improve image quality, but most patients still need glasses

to correct any residual refractive error.

Some clinical schools recommend combining ICRS with surface laser (PRK)

so the patient may eventually be able to stop wearing glasses,

but there are caveats — please discuss this with Dr. Shaarawy at your consultation.

Patients must continue follow-up after ICRS implantation

so that any further corneal progression can be detected early.

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